The present invention is directed to ink compositions, and imaging and printing processes thereof. More specifically, in embodiments the present invention is directed to ink jet ink compositions with improved waterfastness characteristics, and desirable viscosities, and which inks are useful for printing on a variety of substrates, such as paper, and wherein the inks contain colorants, especially pigments, such as carbon black, especially acidic carbon blacks, with associated primary, secondary, and/or tertiary amine complexing components. The inks can be formulated by, for example, adding the amine and carbon black to water, and wherein there is formed a weak network of interaction between the carbon black particles and the amine. The inks of the present invention in embodiments possess an initial high viscosity, for example from about 20 to about 500 centipoise, and a low viscosity when subjected to shearing forces, for example after being ejected from an ink jet head, which low viscosity is, for example, from about 1 to about 10 centipoise, and more specifically, from about 2 to about 5 centipoise (cps), and subsequently, an important return to high viscosity upon removal of the shear forces, for example, once the ink rests on the substrate surface, which viscosity is from about 20 to about 500 centipoise, thereby enabling excellent jettability and excellent image resolution. Of importance with respect to the present invention is the enablement of inks with a high viscosity after shearing, as compared to similar prior art inks with dyes, reference for example U.S. Pat. No. 5,254,159, the disclosure of which is totally incorporated herein by reference, and wherein inks with dyes with amines are disclosed, and which inks are very nonviscous after shearing; for example these inks possess a low viscosity of from about 2 to about 5, thus the image resolution and other image and ink characteristics are inferior when compared to the pigmented inks and developed images thereof of the present invention. Viscosity and surface tensions are important contributing factors in the generation of excellent quality prints on plain papers, that is prints with acceptable edge acuity, or the sharpness of the edge between the printed and nonprinted areas, minimal ink feathering on paper, and characterized, for example, by a desirable uniformity of solid area ink coverage.
The inks of the present invention can be selected for a number of known ink jet printing methods and apparatus, including thermal ink jet, or bubble jet processes as described in, for example, U.S. Pat. No. 4,601,777, U.S. Pat. No. 4,251,824, U.S. Pat. No. 4,410,899, U.S. Pat. No. 4,412,224, and U.S. Pat No. 4,532,530, the disclosures of which are totally incorporated herein by reference, acoustic ink jet processes, reference U.S. Pat. No. 5,688,312, U.S. Pat. No. 5,667,568, U.S. Pat. No. 5,700,316, U.S. Pat. No. 5,747,554, and copending patent application U.S. Ser. No. 641,866, the disclosures of each of the aforementioned patent applications being totally incorporated herein by reference. Many of the components, such as the vehicles, additives, pigments, and the like of the aforementioned copending applications may be selected for the inks of the present invention in embodiments thereof. Rapid drying and excellent, or superior waterfastness, in embodiments of the present invention of from between about 90 to about 99 percent, greater than 95 percent, and more specifically, from about 95 to about 99.5 percent, are of value in rapid printing applications, such as printing by xerography at, for example, a speed of from about 50 to about 100 copies per minutes. Also, in embodiments the inks of the present invention possess water staining resistance.